From: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: the arch/x86 maintainers <x86@kernel.org>,
KVM <kvm@vger.kernel.org>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Peter Zijlstra <peterz@infradead.org>,
Stefano Stabellini <stefano.stabellini@eu.citrix.com>,
Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
LKML <linux-kernel@vger.kernel.org>,
Andi Kleen <andi@firstfloor.org>, Avi Kivity <avi@redhat.com>,
Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Attilio Rao <attilio.rao@citrix.com>, Ingo Molnar <mingo@elte.hu>,
Virtualization <virtualization@lists.linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Xen Devel <xen-devel@lists.xensource.com>,
Stephan Diestelhorst <stephan.diestelhorst@amd.com>
Subject: Re: [PATCH RFC V6 0/11] Paravirtualized ticketlocks
Date: Sat, 31 Mar 2012 09:39:15 +0530 [thread overview]
Message-ID: <20120331040915.GF13345@linux.vnet.ibm.com> (raw)
In-Reply-To: <20120331040745.GC14030@linux.vnet.ibm.com>
* Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> [2012-03-31 09:37:45]:
> The issue is with ticketlocks though. VCPUs could go into a spin w/o
> a lock being held by anybody. Say VCPUs 1-99 try to grab a lock in
> that order (on a host with one cpu). VCPU1 wins (after VCPU0 releases it)
> and releases the lock. VCPU1 is next eligible to take the lock. If
Sorry I meant to say "VCPU2 is next eligible ..."
> that is not scheduled early enough by host, then remaining vcpus would keep
> spinning (even though lock is technically not held by anybody) w/o making
> forward progress.
>
> In that situation, what we really need is for the guest to hint to host
> scheduler to schedule VCPU1 early (via yield_to or something similar).
s/VCPU1/VCPU2 ..
- vatsa
WARNING: multiple messages have this Message-ID (diff)
From: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>,
Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
Ingo Molnar <mingo@elte.hu>,
Linus Torvalds <torvalds@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
the arch/x86 maintainers <x86@kernel.org>,
LKML <linux-kernel@vger.kernel.org>, Avi Kivity <avi@redhat.com>,
Marcelo Tosatti <mtosatti@redhat.com>, KVM <kvm@vger.kernel.org>,
Andi Kleen <andi@firstfloor.org>,
Xen Devel <xen-devel@lists.xensource.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Virtualization <virtualization@lists.linux-foundation.org>,
Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>,
Stephan Diestelhorst <stephan.diestelhorst@amd.com>,
Stefano Stabellini <stefano.stabellini@eu.citrix.com>,
Attilio Rao <attilio.rao@citrix.com>
Subject: Re: [PATCH RFC V6 0/11] Paravirtualized ticketlocks
Date: Sat, 31 Mar 2012 09:39:15 +0530 [thread overview]
Message-ID: <20120331040915.GF13345@linux.vnet.ibm.com> (raw)
In-Reply-To: <20120331040745.GC14030@linux.vnet.ibm.com>
* Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> [2012-03-31 09:37:45]:
> The issue is with ticketlocks though. VCPUs could go into a spin w/o
> a lock being held by anybody. Say VCPUs 1-99 try to grab a lock in
> that order (on a host with one cpu). VCPU1 wins (after VCPU0 releases it)
> and releases the lock. VCPU1 is next eligible to take the lock. If
Sorry I meant to say "VCPU2 is next eligible ..."
> that is not scheduled early enough by host, then remaining vcpus would keep
> spinning (even though lock is technically not held by anybody) w/o making
> forward progress.
>
> In that situation, what we really need is for the guest to hint to host
> scheduler to schedule VCPU1 early (via yield_to or something similar).
s/VCPU1/VCPU2 ..
- vatsa
next prev parent reply other threads:[~2012-03-31 4:09 UTC|newest]
Thread overview: 113+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-21 10:20 [PATCH RFC V6 0/11] Paravirtualized ticketlocks Raghavendra K T
2012-03-21 10:20 ` Raghavendra K T
2012-03-21 10:20 ` [PATCH RFC V6 1/11] x86/spinlock: replace pv spinlocks with pv ticketlocks Raghavendra K T
2012-03-21 10:20 ` Raghavendra K T
2012-03-21 13:04 ` Attilio Rao
2012-03-21 13:04 ` Attilio Rao
2012-03-21 13:22 ` Stephan Diestelhorst
2012-03-21 13:49 ` Attilio Rao
2012-03-21 14:25 ` Stephan Diestelhorst
2012-03-21 14:33 ` Attilio Rao
2012-03-21 14:49 ` Raghavendra K T
2012-03-21 14:49 ` Raghavendra K T
2012-03-21 14:33 ` Attilio Rao
2012-03-21 14:25 ` Stephan Diestelhorst
2012-03-21 13:49 ` Attilio Rao
2012-03-21 13:22 ` Stephan Diestelhorst
2012-03-21 10:21 ` [PATCH RFC V6 2/11] x86/ticketlock: don't inline _spin_unlock when using paravirt spinlocks Raghavendra K T
2012-03-21 17:13 ` Linus Torvalds
2012-03-21 17:13 ` Linus Torvalds
2012-03-22 10:06 ` Raghavendra K T
2012-03-22 10:06 ` Raghavendra K T
2012-03-22 10:06 ` Raghavendra K T
2012-03-21 10:21 ` Raghavendra K T
2012-03-21 10:21 ` [PATCH RFC V6 3/11] x86/ticketlock: collapse a layer of functions Raghavendra K T
2012-03-21 10:21 ` Raghavendra K T
2012-03-21 10:21 ` [PATCH RFC V6 4/11] xen: defer spinlock setup until boot CPU setup Raghavendra K T
2012-03-21 10:21 ` Raghavendra K T
2012-03-21 10:21 ` [PATCH RFC V6 5/11] xen/pvticketlock: Xen implementation for PV ticket locks Raghavendra K T
2012-03-21 10:21 ` Raghavendra K T
2012-03-21 10:21 ` [PATCH RFC V6 6/11] xen/pvticketlocks: add xen_nopvspin parameter to disable xen pv ticketlocks Raghavendra K T
2012-03-21 10:21 ` Raghavendra K T
2012-03-21 10:21 ` [PATCH RFC V6 7/11] x86/pvticketlock: use callee-save for lock_spinning Raghavendra K T
2012-03-21 10:21 ` Raghavendra K T
2012-03-21 10:22 ` [PATCH RFC V6 8/11] x86/pvticketlock: when paravirtualizing ticket locks, increment by 2 Raghavendra K T
2012-03-21 10:22 ` Raghavendra K T
2012-03-21 10:22 ` Raghavendra K T
2012-03-21 10:22 ` [PATCH RFC V6 9/11] x86/ticketlock: add slowpath logic Raghavendra K T
2012-03-21 10:22 ` Raghavendra K T
2012-03-21 10:22 ` [PATCH RFC V6 10/11] xen/pvticketlock: allow interrupts to be enabled while blocking Raghavendra K T
2012-03-21 10:22 ` Raghavendra K T
2012-03-21 10:22 ` [PATCH RFC V6 11/11] xen: enable PV ticketlocks on HVM Xen Raghavendra K T
2012-03-21 10:22 ` Raghavendra K T
2012-03-26 14:25 ` [PATCH RFC V6 0/11] Paravirtualized ticketlocks Avi Kivity
2012-03-26 14:25 ` Avi Kivity
2012-03-27 7:37 ` Raghavendra K T
2012-03-27 7:37 ` Raghavendra K T
2012-03-28 16:09 ` Alan Meadows
2012-03-28 18:21 ` Raghavendra K T
2012-03-28 18:21 ` Raghavendra K T
2012-03-29 9:58 ` Avi Kivity
2012-03-29 9:58 ` Avi Kivity
2012-03-29 18:03 ` Raghavendra K T
2012-03-29 18:03 ` Raghavendra K T
2012-03-30 10:07 ` Raghavendra K T
2012-03-30 10:07 ` Raghavendra K T
2012-04-01 13:18 ` Avi Kivity
2012-04-01 13:18 ` Avi Kivity
2012-04-01 13:48 ` Raghavendra K T
2012-04-01 13:48 ` Raghavendra K T
2012-04-01 13:53 ` Avi Kivity
2012-04-01 13:53 ` Avi Kivity
2012-04-01 13:56 ` Raghavendra K T
2012-04-01 13:56 ` Raghavendra K T
2012-04-02 9:51 ` Raghavendra K T
2012-04-02 9:51 ` Raghavendra K T
2012-04-02 12:15 ` Raghavendra K T
2012-04-02 12:15 ` Raghavendra K T
2012-04-05 9:01 ` Avi Kivity
2012-04-05 9:01 ` Avi Kivity
2012-04-05 10:40 ` Raghavendra K T
2012-04-05 10:40 ` Raghavendra K T
2012-04-02 9:51 ` Raghavendra K T
2012-04-05 8:43 ` Raghavendra K T
2012-04-05 8:43 ` Raghavendra K T
2012-03-28 16:37 ` Alan Meadows
2012-03-30 20:26 ` H. Peter Anvin
2012-03-30 20:26 ` H. Peter Anvin
2012-03-30 22:07 ` Thomas Gleixner
2012-03-30 22:07 ` Thomas Gleixner
2012-03-30 22:18 ` Andi Kleen
2012-03-30 22:18 ` Andi Kleen
2012-03-30 23:04 ` Thomas Gleixner
2012-03-30 23:04 ` Thomas Gleixner
2012-03-31 0:08 ` Andi Kleen
2012-03-31 0:08 ` Andi Kleen
2012-03-31 8:11 ` Ingo Molnar
2012-03-31 8:11 ` Ingo Molnar
2012-03-31 4:07 ` Srivatsa Vaddagiri
2012-03-31 4:07 ` Srivatsa Vaddagiri
2012-03-31 4:09 ` Srivatsa Vaddagiri [this message]
2012-03-31 4:09 ` Srivatsa Vaddagiri
2012-04-16 15:44 ` Konrad Rzeszutek Wilk
2012-04-16 15:44 ` Konrad Rzeszutek Wilk
2012-04-16 16:36 ` [Xen-devel] " Ian Campbell
2012-04-16 16:36 ` Ian Campbell
2012-04-16 16:42 ` Jeremy Fitzhardinge
2012-04-16 16:42 ` Jeremy Fitzhardinge
2012-04-17 2:54 ` Srivatsa Vaddagiri
2012-04-17 2:54 ` Srivatsa Vaddagiri
2012-04-01 13:31 ` Avi Kivity
2012-04-01 13:31 ` Avi Kivity
2012-04-02 9:26 ` Thomas Gleixner
2012-04-02 9:26 ` Thomas Gleixner
2012-04-05 9:15 ` Avi Kivity
2012-04-05 9:15 ` Avi Kivity
2012-04-02 4:36 ` [Xen-devel] " Juergen Gross
2012-04-02 4:36 ` Juergen Gross
2012-04-02 9:42 ` Ian Campbell
2012-04-02 9:42 ` Ian Campbell
2012-04-11 1:29 ` Marcelo Tosatti
2012-04-11 1:29 ` Marcelo Tosatti
2012-03-31 0:51 ` Raghavendra K T
2012-03-31 0:51 ` Raghavendra K T
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